The present invention relates to a system and method for rubber coated roll inspection and, more particularly, to an infrared inspection system cooperating with an induction heating system for non-destructive inspections of rubber coated rolls looking for de bonds between the metal core and rubber coating.
Industrial sites such as paper mills utilize large cylindrical rolls to process various products, such as paper pulp into sheets. The rolls are typically rubber coated and form one part of a large and expensive apparatus that is usually run continuously to maximize factory output. De bonding between the rubber coating and the base of the roll can occur over time, resulting in catastrophic consequences for the paper machine, particularly if the rubber coating is fully detached and pulled through the rest of the machine. The damage to the machine, the cost of re-coating the roll, and the factory downtime are of course cause for significant concern.
Some previous methods for rubber coating bond evaluation utilize acoustic emission, ultrasonic probes, and physical probing. Acoustic emission in a factory environment, however, is a difficult prospect as background noises and vibrations are difficult to effectively screen out, and reliable results have not been obtained. Ultrasonic probes have been used with mixed success, but high false alarm rates and subjectivity of results due to the hand held probing has limited the acceptance of this method. Moreover, roll inspection time is high. Physical probing with solid implements is also subjective and typically does not provide satisfactory results. The method includes xe2x80x9cbangingxe2x80x9d the roll followed by listening to and feeling the, response, or attempting to induce minor displacements in the rubber coating and watching for variations.
In an exemplary embodiment of the invention, a method of detecting debonding in coated paper rolls includes the steps of (a) supporting a roll for inspection, (b) evenly heating or cooling the roll, and (c) observing a thermal transient of the roll generated according to step (b). Step (b) may be practiced by securing an induction coil around the roll, activating the induction coil, and axially displacing the induction coil along a length of the roll. The induction coil is preferably supported by a robotic vehicle, wherein the axial displacing of the induction coil is practiced by controlling the position of the robotic vehicle. Step (c) is preferably practiced by capturing infrared images of the heated roll and determining de bonded areas according to the infrared images, which may be displayed on a display or the like.
In another exemplary embodiment of the invention, an inspection system for detecting debonding in coated paper rolls includes a heating or cooling unit attachable to a roll for evenly heating or cooling a roll, and a receptor observing a thermal transient of a roll generated by the heating or cooling unit.